Answer:
Step-by-step explanation:
We would assume a binomial distribution for the Americans that own answering machines. The formula is expressed as
P(x = r) = nCr × p^r × q^(n - r)
Where
x represent the number of successes.
p represents the probability of success.
q = (1 - r) represents the probability of failure.
n represents the number of trials or sample.
From the information given,
p = 70% = 70/100 = 0.7
q = 1 - p = 1 - 0.7
q = 0.3
n = 5
x = r = 3
Therefore,
P(x = 3) = 5C3 × 0.7^3 × 0.3^(5 - 3)
P(x = 3) = 10 × 0.343 × 0.09
P(x = 3) = 0.3087
b) mean = np = 5 × 0.7 = 3.5
